2016 July 4

LED lighting for bathroom

I’ve been making a project of replacing all the fluorescent lights in the house with LED lights. For the compact fluorescents, this is easy—when a CFL bulb burns out, I replace it with an LED bulb of similar brightness. The tubular fluorescents in the kitchen, the bathroom cove lighting, and the dining-room cove lighting are more of a project.

This weekend I finally got the fluorescent lighting in the cove around the skylight in bathroom replaced with LED strip lights. Unlike the kitchen LED lights, I did this project entirely myself.

First, I removed the old fluorescent fixtures (2 40W and 2 20W fixtures) and replaced them with an outlet in the corner of the cove. Those fluorescent fixtures were 24 years old, from the 1992 remodel of the bathroom, and I’d never really liked them much—the ballasts tended to hum, and the bulbs needed to be replaced every few years.

I then cleaned and painted the interior of the cove to make it more reflective (it had just a thin coating of primer before). It was a bit awkward working at the top of the ladder, and I managed to get a couple of smears of the semigloss paint on the walls of the skylight, not matching the previous matte white walls. Luckily they’re not too visible unless you are looking for them.

I measured lengths of LED strips to fit the cove, cut the strips with wire cutters, shaved off the silicone waterproofing where I needed to make connections, soldered on flexible wires, and covered the connections with heat-shrink tubing. I also made a little barrel-connector-to-screw-terminals board to distribute the 12V power to two strips, with each strip connected to a different pair of screw terminals.

Here is the outlet in the corner of the cove—because the cove was deep enough for the old fluorescent fixtures, it was deep enough to conceal the outlet box mounted vertically. The 12V wall wart connects to two LED strips, each of which covers half the perimeter.

The strips have adhesive on the back, so I just stuck them to the middle of the cove.

At two corners of the cove, I used flexible wires to connect separate straight strips.

From below the light is a soft glow—there is additional separately controlled can lighting over the mirrors and over the shower stall, so the cove lighting around the skylight is only to provide diffuse ambient light, not bright task light.

I bought 5m of 60 LED/m strip lighting from Aliexpress and used 3.9m of the strips. I measured the full 5m length as taking 1.13A at 11.5V (13W). I had expected the LED strips to take much more power, since the seller advertised them as 14.4 W/m, but that seems to have been a mistake (or a lie).

The 3.9m I used should take about 10.1W, but the wall wart is using 20W, so it is only about 50% efficient. I may want to get a smaller, more modern wall wart, to get higher efficiency. There is a little less light from the 20W of LED lighting than from the 100W of fluorescent lighting, but not as much less as one might expect, and the soft yellow light is plenty for night-time trips to the bathroom.

The amount of light from the cove is much less than the light from one row of the LED puck lights in the kitchen, though the power consumed is similar (20W for the bathroom, 22W for one row of the kitchen lights). The differences are

direct illumination by the pucks vs reflection off the skylight walls for the cove lighting,

3000K for the pucks vs. very yellow light for the cove, and

efficient modern wall wart for the pucks vs. old, inefficient wall wart for the cove.

My wife rather likes the warm yellow light, so I’ll leave it alone for now. If I get irritated with it, I can always rip out the LED strips and put in new ones (the cost of the LED strips is < $20).